In sprinkler systems in buildings as, for example, in multi-floor buildings, garages, skyscrapers and so on, it is known to branch from a water supplying riser at each building floor a floor branch conduit in which, upstream of the respective water distribution net comprising the sprinkler heads are to be typically provided a drain valve for draining said sprinkler net, a test valve, a fitting provided with observation windows for detecting the flowing water flow, and an electrical alarm device, as required for example by the United States Fire Suppression Specifications.
The purpose of said arrangement is from time to time to test the operability of the signal or alarm circuit (the signal of which may be a local audible signal and/or an alarm signal transmitted to the nearest Firemen Station) in case of real or simulated (by means of the arrangement test function) water delivering by at least one sprinkler head as well as to allow, after having previously closed the upstream main valve or general control valve, a draining of the sprinkler system, for example for maintenance purposes or replacing one or more of the sprinkler heads.
The valve devices have been recently joined to form an integrated multi-valve units which are able to carry out both the test and drain functions and incorporate said observation windows for detecting the water flow, as disclosed for example in the U.S. Pat. No. 4,655,078 to Augustus W. Johnson and U.S. Pat. No. 4,643,224 to Robert Rung et al.
A similar valve incorporating an observation window is also disclosed in the U.S. Pat. No. 4,741,361 to George J. McHugh.
The valve disclosed in U.S. Pat. No. 4,655,078 comprises a conventional ball shutter, that is a shutter having a through channel the inlet and outlet openings of which are defined by two opposite ball flattenings and have a diameter similar to the diameter of the valve inlet and outlet channels. In said shutter is provided a second hole which extends diametrically and is coplanar with respect to said through channel, encloses a certain angle with the latter and has a small diameter which substantially corresponds to the internal diameter of the inlet channel of each sprinkler head. The shutter is supported in a conventional way between two opposite gaskets placed in correspondent seats provided in a closed chamber housing the shutter.
The ball shutter according to the U.S. Pat. No. '078 differs therefore from the known ball shutters because it presents said second through channel and therefore, the ball shutter can be rotated around the vertical axis thereof in three positions, and more exactly in both the conventional valve closing and opening positions by use of the known through channel with a bigger hole (here used for the draining function), with the additional possibility to open the valve by using the through channel having the smaller diameter (testing function). Two diametrically opposite observation windows are housed within the valve outlet channel.
As in the conventional ball valves also in the valve according to the U.S. Pat. No '078 the water flow is intercepted at the inlet side. The valve disclosed in the U.S. Pat. No. '078 is of a linear type indeed, that is with coaxial inlet and outlet channels, which allows quicker working and assembling steps and smaller overall dimensions as well as a smaller material expenditure with respect to valves having a L-shaped or a T-shaped valve body. In reality, the smaller material expenditure achievable with the valve disclosed in U.S. Pat. No. '078 is negligible as, with respect to the conventional ball valves, the proposed shutters have a bigger diameter due to the requirement of working a second through channel in a coplanar and angularly offset position with respect to the conventional through channel. A further disadvantage due to the presence of both through channels in the ball shutter is to be seen in the dimensional limits of such ball shutter, so that the teaching of Johnson can be surely carried out with medium or large ball shutters, for example with shutters having a diameter of 2-1/2" as stated in Johnson's patent.
However, said teaching can not be carried out with shutters having a smaller diameter, for example of 1" or 3/4", as frequently desirable indeed.
Another drawback of the valves according to U.S. Pat. No. '078 is to be seen in the fact that both rectilinear through channels have a uniform diameter, so that the outlet liquid flow is practically uniform and regular, that is the liquid flow is practically without any turbulence, so that it is rather difficult to visually detect the flowing liquid by observing through the observation windows.
It is further stressed that the ball shutter seal is achieved by means of a strong pressure onto the shutter clamped between two opposite supporting gaskets, which, together with the fact that the ball in closing position (which is typically adopted in sprinkler systems) within the inlet channel is exposed to the water pressure, whereas in the outlet channel practically exists an atmospheric pressure, causes that the control couples, that is the opening couples, require a rather intensive manual effort.
It is further stressed the fact that sandy matter that may be wedged between the gaskets and the shutter is in fact captured therebetween so that by rotating the shutter gasket wearings may occur, which jeopardize the valve seal.
The U.S. Pat. No. 4,643,224 discloses a double valve with two opposite valve chambers which are in fluid communication with the inlet channel and singularly house one of two shutters with associated outer control hand-wheel. Both outlet channels of said chambers join in a common outlet channel. One valve is provided for the testing function whereas the other one is provided for the draining function. Within the outlet channel of the testing chamber is housed a flow detecting device in the form of a transparent cylinder housed in the valve body and provided with a small delivering hole which opens out in a bigger chamber in which, due to the different pressures upstream and downstream of said delivering hole, cavitations are formed which facilitate the visual detection of the flowing flow. Also the valve disclosed in the U.S. Pat. No. '224 is of a linear type. However, in such valve the construction of two distinct opposite valves and the observation cylinder, as well as the necessary large room which is necessary for an easy access to both control hand-wheels are rather costly. Another drawback resides in the fact that the valve body is to be produced by casting and will therefore be affected by the typical disadvantages of castings like porosity, cavities and cracks in the structure, rather thick walls for overcoming above discussed drawbacks, as well as asymmetric working for housing both shutters and said observation cylinder.
The U.S. Pat. No. 4,741,361 discloses a valve with a T-shaped configuration in which the axes of the inlet and outlet channels are at 90.degree. to one another, and the third opening is not operable and is closed by a plug. Also by eliminating said opening closed by the plug the valve would present in any case a L-shaped configuration, that is with inlet and outlet channels at an angle of 90.degree.. This configuration requires on the one hand a greater installation room with respect to rectilinear valves, that is valves with coaxial inlet and outlet channels. Differently from the conventional ball shutters, the shutter disclosed in the U.S. Pat. No. '361 has the conventional through channel having, diametrically opposite, the conventional opening and an opening with a smaller diameter. At right angle to said through channel is provided a third opening which opens out in said through channel and has a diameter similar to that of said through channel. Both openings with the large diameter are defined by opposite flattenings.
In this shutter are cleverly provided two diametrically opposite slots for housing the profiled end of the control stem, so that the proposed valve can be configured for left-handed or right-handed operation. Also in the U.S. Pat. No. '361 the ball shutter is supported between two opposite annular gaskets housed in the valve body. Therefore, the chamber housing the ball shutter, like the valve disclosed in the U.S. Pat. No. '078, forms a closed chamber without any operable function. Also for the valve proposed in the U.S. Pat. No. '361 is required a strong opening couple.
Further, a valve manufactured by the applicant is known with a rectilinear valve body in two parts and a multi-opening ball shutter supported between two opposite gaskets in an open chamber which is in fluid communication with the inlet chamber through a cage-like configuration of a valve half-body forming the inlet channel. In said cage-like half-body is supported the shutter gasket at the inlet side. In the ball shutter is provided a third flattening defining the small opening of the through channel. Also said valve is affected by said two drawbacks due on the one end to the possible wearings of the annular gasket supporting the shutter, and on the other hand to the necessary strong opening couple. The three necessary positions are snaply defined by a removable engagement between a ball springingly housed within the valve body and the apertures provided at 90.degree. to one another on a common circle in a rotatable plate which can be rotated together with the shutter control lever provided with stop tongues cooperating with a projection of the valve body in order to delimit therewith a 180.degree. rotation of the control lever, that is of the ball shutter.